There are two versions of the Fluke 481 Ion Chamber Survey Meter available, the Fluke 481 and the Fluke 481-DESI.The Fluke 481-DE-SI has a temperature sensor that is used to adjust for offset drift due to temperature. Please note that readings are not corrected for changes in air density due to pressure and temperature.
Also, the operating ranges, detector, and response time between the two models differ, as follows:
Operating Ranges:
481: 0 to 5 mR/h, 0 to 50 mR/h, 0 to 500 mR/h, 0 to 5 R/h, 0 to 50 R/h
481-DE-SI: 0 to 50 µSv/h, 0 to 500 µSv/h, 0 to 5 mSv/h, 0 to 50 mSv/h,
0 to 500 mSv/h
Detector
481: 349 cc volume air ionization chamber; phenolic chamber wall
246 mg/cm2. Chamber window is composed of 6.6 mg/cm2 Mylar. A
coating of graphite has been applied to the walls to make them
conductive. The collection potential is -63 Volts. The Chamber is
vented through the desiccant
481-DE-SI: In order to achieve energy response consistent with
measurements of H*(10) as required by ICRU report 47, aluminum has
been added to the back wall, 38 % of the side wall area, and to the
beta slide. With the Beta Shield open, the 481 can measure skin dose
at H* (0.07), and Deep Dose H* (10) with the Beta shield closed.
Response Time
Time measured from 10 % to 90 % of final value for a step
increase/decrease in radiation rate such that a range change does not
occur:
481: 0 to 5 mR/h, range: 8 seconds. 0 to 50 mR/h, range: 2.5 seconds.
0 to 500 mR/h range: 2 seconds. 0 to 5 R/h, range: 2 seconds. 0 to
50 R/h, range: 2 seconds
481-DE-SI: 0 to 50 µSv/h, range: 8 seconds. 0 to 500 µSv/h, range:
2.5 seconds. 0 to 5 mSv/h, range: 2 seconds. 0 to 50
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Answered by Anonymous